I'm thinking about using HDPE sheet to face a new router table fence, and
was wondering how well this stuff mills. I thought about buying it in 1"
thickness and then jointing and planing it down to about 3/4". But will the
surface still be smooth after milling? And should I just buy it in 3/4"
thickness and just trust that it is nice and flat as is?
I've never cut it in a wood planer. It cuts nice using an end mill. Might
bung up your cutter depending on design. I'd suggest getting 3/4" then
planing down only a few thou for flatness. Probably the HDPE stock will be
truer than the wood you are cutting.
My experience is that you will be better off milling it down to the size you
want but it also depends on what and where you buy it. If you purchase a
cutting board and cut it to make (guides, fences, inserts, etc.) it will
usually need to be planed in order to have flat, parallel surfaces.
The pieces of HDPE that are on my Xacta (Jet) TS fence were anything but
flat and I milled them down by using double-back tape to secure them to an
MDF carrier and running them thru the planer. Take super light cuts and be
sure the piece is pushed down flat to the carrier board using tape so it
covers the width and length of the piece. If it doesn't, that will get
telegraphed thru when you plane it.
In many ways, HDPE is like wood (it even floats).
I've milled HDPE with a Delta 12-1/2" planer ... it gets a bit tricky as you
get thinner than say 3/8" ... because the material loves to flex. Thicker
and I get a beautiful finish ... just go a 1/4 turn a pass (what ... 1/128"
or so). Very smooth surface.
I wouldn't expect the thickness to be correct. Most of what I've been using
has been extruded ... the 1" thickness is "nominal" and has varied as much
as -.02 to + .05 ... in one sheet. Cast is just as bad. Mind you ... this is
sheet goods, not a finished part, so you can expect it to be a bit oversized
(though the undersized confused me ... no matter how many times I planed it,
it was always too thin).
HDPE is a lot like wood, in that if you get a piece that has been case
hardened (extrusion temperature got out of wack ... outside surfaces
different density than the middle) it WILL bind on a table saw and try to
kick back. I'm REALLY happy that my direct drive sears table saw is
underpowered ... gave me enough warning to hit the kill button before things
went flying. Wasn't an alignment issue ... the kerf closed up halfway
through the cut!
HDPE mills with common woodworking router bits ok ... better results with
cutters specifically ground for HDPE (only if you're doing a lot though).
You'd enjoy watching a 6" long, 1/2" diameter router bit in a 3-1/2 HP
router hogging curled pieces of HDPE ... no hope for catching them all with
the dust hood.
HDPE turns pretty easily too ... great for teaching someone the basics of
lathe work ... no sudden defects to blow out on you.
If you want, you can have my scraps for the shipping cost. I'm in North
Carolina, near Greensboro if you have a mind to drive by and haul away the
entire pile of scrap pieces. One inch thick, black HDPE; let me know what
length and width you'd like. If I have a packing tube that will fit it, all
you'll be out is the UPS charge. Bulk cost is something around four cents
per cubic inch (not that you'll have to pay for this stuff ... just letting
you know what you'll see if you go to purchase any). Weight is approximately
.53 oz per cubic inch (48x96x1 sheet weighs around 154 pounds).
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